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Biology LibreTexts

7: Molecular Genetics I - Molecular Biology of Gene Expression

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Thus far, we've explored how phenotypic traits -- monogenic and complex -- are passed from one generation to the next via heritable changes in genetic material. However, we haven't given much thought to mechanistically how a gene is expressed as a trait. Doing so requires adopting an explicitly molecular genetic approach, where "genes" are sequences of DNA encoding proteins -- they are transcribed to make messenger RNA, which is translated to make a polypeptide, which folds into a functional protein. And proteins are the "do"ers of the cell -- molecular machines that do chemistry, transmit information, transform energy, etc. That means that proteins and their functions are directly responsible for an organism's phenotype.

Understanding how cells express genes -- the molecular basis of transcription and translation -- is important for two reasons. First, "how does genotype become phenotype" is a central question in the study of genetics. And second, a solid understanding of transcription and translation is important so we can subsequently consider how cells change when, where and how much a gene is expressed. That will be the subject of the next chapter.

Learning Objectives

Upon mastering the material in this chapter, you should be able to:

  • Describe how transcription is initiated and terminated in prokaryotes and eukaryotes

  • Predict how mutations in non-coding sequences affect gene expression

  • Describe mRNA processing in eukaryotes

  • Describe how tRNAs are used as “adapter” molecules

  • Explain how the wobble hypothesis explains how 61 codons are translated with only 40 tRNAs

 


7: Molecular Genetics I - Molecular Biology of Gene Expression is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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